The subject of the invention is a navigation system for a motor vehicle containing a central processor connected to an input unit and to an output unit, to position determination means and to a storage element for map data, and means for associating an ascertained vehicle position with a data record, stored in the storage element, of the map data.
Such a navigation system is known from EP 0 363 396 B1, for example. Navigation systems in motor vehicles perform a number of functions. A first function is the calculation of a route between a starting location and a destination, with it generally being possible to choose between the fastest and the shortest route. After route calculation has been carried out, the task of the navigation system is to guide the motor vehicle driver to the destination. To this end, it is necessary for constant position determination to be carried out for the motor vehicle and for the motor vehicle position ascertained in this way to be matched to the map data stored in the navigation system. In this context, the route planning information is output via an output unit, with the information generally being output both visually and audibly. Such a known navigation system significantly assists a driver on journeys in an area with which he is not familiar. In particular, he is not obliged to be constantly looking at signs showing directions at the edge of the road. Nevertheless, the driver still needs to take note of a sometimes large number of other road signs showing regulations and restrictions. However, on the one hand, road signs at the edge of the road are easily overlooked, and, on the other hand, the driver may be unclear as to which particular restrictions are current on the section of road on which he is driving, especially when signs are frequently changing. This applies particularly to speed restrictions, for example. This problem may arise to a large extent particularly on inter-urban journeys with changing speed restrictions.
WO 97/35196 discloses electronic road signs. The electronic road sign has a transmitter transmitting the meaning of the road sign to a passing motor vehicle. The motor vehicle contains a corresponding receiver which receives the data transmitted by the electronic road sign, processes it and displays it using a display unit. The driver can thus always find out about the traffic restrictions existing on the section of road on which he is currently driving. However, a disadvantage of this is the high costs of the system, since each road sign needs to be provided with appropriate electronic equipment. Furthermore, an additional receiver and a display unit are also required in the motor vehicle itself.
The object of the invention is to modify a navigation system of the type described in the introduction such that, besides the route planning information, other important information relating to the road can also be displayed and can thus assist the driver of the vehicle.
The object is achieved in a navigation system of this generic type as a result of the feature that the storage element stores information about traffic restrictions which is part of a data record of the map data, and traffic restrictions relevant to the ascertained vehicle position can be displayed on the display unit.